Our laboratory performs basic and clinical studies of the B19 parvovirus, the only member of the Parvoviridae family pathogenic in humans. Acute infection causes fifth disease, a childhood rash illness and a polyarthralgia syndrome in adults. In patients with underlying hemolysis, acute infection results in transient aplastic crisis. In patients with underlying immunodeficiency, virus infection persists and causes chronic anemia; parvovirus infection is a cause of anemia in patients with AIDS. The virus is tropic for erythroid progenitor cells. During the past year, progress has been made in three areas: 1) virus structure; 2)immunogenicity and vaccine formulation; 3)non-structural protein structure and function. We have identified the cellular receptor for B19 parvovirus as globoside or P antigen, a glycolipid present on red cells and erythroid precursor cells. The crystal structure of B19 parvovirus empty capsids has been determined at low resolution and shows expected similarities to the structure of canine parvovirus as well as a remarkable difference in the surface conformation. For immunogenicity studies, the unique region of the minor capsid protein has been shown to contain potent linear epitopes that elicit neutralizing antibody activity in animals. We have shown that enrichment for VP1 greatly increases the neutralizing antibody response in three species of animals; dose ranging and adjuvant studies have been completed in preparation for human vaccine trials. Finally, recombinant nonstructural protein of B19 parvovirus has been purified using high pressure liquid chromatography. A nuclear localizing region has been identified.